Tuesday 23 January 2007 19.16 EST
First published on Tuesday 23 January 2007 19.16 EST

Let's stop the pretending: Blatcherism has been an inexcusable missed opportunity to take Britain in a completely different direction (towards Denmark rather than America) and it has significantly contributed to our spiralling rate of mental illness.

I have discovered that citizens of English-speaking nations are twice as likely to suffer mental illness as ones from mainland western Europe.

Specifically, my analysis reveals that over a 12-month period nearly one-quarter (23%) of English speakers suffered, compared with 11.5% of mainland western Europeans.

What explains such a massive difference? It is extremely unlikely to be genes - English-speakers largely come from the same gene pool as Europeans. Indeed, the World Health Organisation study of mental illness in 15 nations, on which my analysis is based, strongly implies that genes play little or no part in explaining national differences in mental illness, and that among developed nations economic inequality is highly significant.

The US is by some margin the most mentally ill nation, with 26.4% having suffered in those 12 months. This is six times the prevalence of Shanghai or Nigeria, a huge discrepancy. Again, genes do not explain it - studies show that when Nigerians move to America, within a few generations they develop American prevalences.

It is looking increasingly likely that major flaws in studies of identical twins - on which the genetic case has wholly rested until recently - have led to a large exaggeration of the role of genes. Molecular genetics (direct studies of DNA) has disproved the idea that there are single genes for almost any mental illnesses and may eventually prove that genes play little role at all.

It is selfish capitalism which largely explains the greater prevalence among English-speaking nations. By this I mean a form of political economy that has four core characteristics: judging a business's success almost exclusively by share price; privatisation of public utilities; minimal regulation of business, suppression of unions and very low taxation for the rich, resulting in massive economic inequality; the ideology that consumption and market forces can meet human needs of almost every kind. America is the apotheosis of selfish capitalism, Denmark of the unselfish variety.

Selfish capitalism causes mental illness by spawning materialism, or, as I put it, the affluenza virus - placing a high value on money, possessions, appearances (social and physical) and fame. English-speaking nations are more infected with the virus than mainland western European ones. Studies in many nations prove that people who strongly subscribe to virus values are at significantly greater risk of depression, anxiety, substance abuse and personality disorder.

In 1997 we trusted that Blair was only pretending to be Blatcher. Most of us signed up to his selfish capitalist manifesto thinking that it would really be unselfish - that the third way bullshit was really code for this. Alas, it was not.

Yes, there has been much more spent on education and health than the Tories would have done. But private companies now own many of the buildings, and criminal rates of interest and privatisation are the real goal. The only thing about which I am totally convinced is the reduction in child poverty. Otherwise, Blatcher and Thatcher have been indistinguishable.

The net consequence for true Labour voters has been to force us to become more or less severely virus-infected. Above all, the clamping on of nosepegs to vote for these closet selfish capitalists has been incredibly harmful to our mental health, making self-contradictory frauds of too many. Doctors, teachers and public service workers have had to pretend that money is more important than patients or pupils - as it all too manifestly is to Blatcher and his acolytes, personally and politically.

For Brown to get me out on polling day, a major apologia will be required: "I am terribly sorry. I promise not to perpetuate the Nouveau (riche) Labour catastrophe for another day. Like everyone else, I was fooled by Tony."

· Oliver James's book Affluenza - How to Be Successful and Stay Sane is published today.